// 代码索引 3-3-2-1
#include <Eigen/Dense>
#include <iostream>
 
int main()
{
    Eigen::ArrayXXf a(3,3);
    Eigen::ArrayXXf b(3,3);
    a << 1,2,3,
         4,5,6,
         7,8,9;
    b << 1,2,3,
         1,2,3,
         1,2,3;
        
    // Adding two arrays
    std::cout << "a + b = " << std::endl << a + b << std::endl << std::endl;
    
    // Subtracting a scalar from an array
    std::cout << "a - 2 = " << std::endl << a - 2 << std::endl;
}